1. Field of the Invention
The present invention relates to methods and apparatus for forming an image using inkjet recording. More particularly, the present invention relates to methods and apparatus for forming an image using intermediate transfer inkjet recording, in which an ink image is formed on a surface of an intermediate transfer medium and then transferred to a recording medium to form an ink image on the surface of the recording medium, and to a method and apparatus for forming an image by inkjet recording, in which an ink image is directly formed on a recording medium.
2. Description of the Related Art
Various measures have conventionally been taken to accelerate drying of ink and to maintain high concentration with respect to methods for recording an image on plain paper by inkjet recording.
One such measure for accelerating drying of ink is to use easily dryable components for the ink in order to accelerate drying of the ink itself. However, since ink itself dries easily, ink within an inkjet recording head (hereinafter, sometimes referred to simply as xe2x80x9crecording headxe2x80x9d) also dries, whereby the ink is either jetted unevenly or cannot be jetted at all due to the ink thickening and adhering to the interior of the recording head. This leads to a remarkable reduction in image quality and dependability. In addition, when a color image is recorded on plain paper, the amount of ink jetted per unit area is twofold or more of that of a monochrome image. There are thus problems in that it becomes easy for images to bleed, fixation to be deficient, and the paper to cockle due to head abrasion.
Another measure for accelerating drying of ink is to dispose means for drying the ink (e.g., a heater) in the image forming apparatus itself, as disclosed in Japanese Patent Application Laid-open (JP-A) No. 62-130863. However, when a recording medium is warmed to accelerate drying of the ink, substances that evaporate from the ink moisten the jetting surface of the recording head, whereby the ink is either jetted unevenly or cannot be jetted at all, which leads to a remarkable reduction in image quality and dependability. In addition, when a color image is recorded on plain paper, the amount of ink jetted per unit area is twofold or more of that of a monochrome image, there are thus problems in that it becomes easy for images to bleed and fixation to be poor. This tendency becomes more pronounced when the speed at which inkjet recording is conducted is increased.
A third measure for accelerating drying of ink is to employ multipass printing and repeatedly conduct printing several times, namely, to combine multi passes and staggered printing to thereby restrict the amount of ink jetted at one time and reduce fixing time. However, this leads to a reduction in recording speed and cannot be applied when the amount of ink jetted is increased for color images.
One measure to maintain high concentration is to change the ink components and dye concentration within the ink to thereby leave as much dye as possible on the paper. However, since ink itself dries easily, ink within the recording head also dries, whereby the ink may be either jetted unevenly or not at all due to the ink thickening and adhering to the interior of the recording head. This can lead to a remarkable reduction in image quality and dependability.
Another measure to maintain high concentration is to repeatedly conduct printing several times by combining multipass and staggered printing, whereby dye concentration per unit area is increased. However, this can in turn adversely affect fixation and lower recording speed.
When images are thus recorded by inkjet recording, there are drawbacks in that ordinary dyes are not resistant to water and characters bleed when they come into contact with saliva or wet hands. Although pigment inks and water-resistant dyes have been used to try to overcome these problems, there are problems in that it becomes necessary to use pigment inks and water-resistant dyes that have been made insoluble to aqueous solutions, and the recording head becomes clogged.
Although the adoption of pigment ink has been investigated as a measure to impart water-resistance to ink, there are problems in that expensive recovering means become necessary to avoid reduction in dependability, hues are lowered in color recording, and light transmittance is poor when recording on OHP paper. Moreover, adopting water-resistant ink leads to problems in that means similar to pigment inks are necessary to avoid reduction in dependability, and when water-resistance is imparted to a color dye, the light absorption spectrum of the dye itself increases and there is a drop in color reproducibility when color recording is conducted.
JP-A No. 64-63185 discloses using an inkjet recording head to adhere onto a recording paper a colorless ink that renders a dye insoluble. Additionally, JP-A No. 5-202328 discloses using both an ink that includes a chemical dye having a carboxyl group and a polyvalent metal salt solution for rendering a dye insoluble and printing the ink after the polyvalent metal salt solution is printed, to thereby obtain a water-resistant image with no color bleeding. However, there are problems in that, on the one hand, when the colorless ink that renders the dye insoluble or solutions such as the polyvalent metal salt solution come into contact with the ink in the image forming apparatus, the apparatus may break down and, on the other hand, the amount of ink jetted per unit area is about twofold in the case of a monochrome image and at least about 1.5-fold in the case of a color image, and it becomes easy for the recording medium to cockle and for fixation to be deficient.
In order to overcome these problems in the conventional art, a method and apparatus for forming an image have been proposed where hydrophilic resin particles are applied to a recording medium to retain ink, ink is jetting onto the hydrophilic resin particles with an inkjet recording head, and then the hydrophilic resin particles are fixed on a recording material to form the image (e.g., JP-A No. 5-96720). However, there are problems with the hydrophilic resin particles in that the reaction of the ink with a dye and weather-resistance is insufficient. There are also problems such as irregularity, deterioration of image quality, migration and the like due to swelling of the hydrophilic resin particles.
In conventional inkjet recording, phenomena such as floating ink generated by ink mist re-adhering to the recording head and ink droplets jetted onto the recording medium rebounding have also been observed. There is thus the potential for the recording head disposed downstream from the printing section to experience problems due to the ink droplets adhering to the recording head. Moreover, in order to obtain high image quality, it is necessary to enhance the precision of the position to which the ink droplets are jetted by decreasing the distance between the recording head and the recording medium and increasing the speed at which the ink is jetted, whereby the aforementioned problems experienced by the recording head become more pronounced.
An object of the present invention is to solve the various problems in inkjet recording described above. More particularly, an object of the present invention is to provide a method and an apparatus for forming on a recording medium, such as plain paper, an image whose resistance to water and light is improved and whose image quality is enhanced, with printing speed being increased due to drying of ink being accelerated. This object is achieved by the present inventions.
According to a first aspect of the invention, the present invention relates to a method for forming an image comprising at least the steps of: forming a layer including resin particles on a surface of an intermediate transfer medium; recording the image by jetting ink from an inkjet recording head onto the resin particle layer so that the ink is retained in cavities of the resin particle layer; and transferring the resin particle layer retaining the ink to a recording medium to fix the resin particle layer thereto.
According to the first aspect of the invention, the present invention also relates to an apparatus for forming an image comprising at least: an intermediate transfer medium; means for forming a layer including resin particles on a surface of the intermediate transfer medium: means for recording the image by jetting ink from an inkjet recording head onto the resin particle layer so that the ink is retained in cavities of the resin particle layer; and means for transferring the resin particle layer to a recording medium to fix the resin particle layer thereto.
The action and effects of the invention are as follows.
First, the resin particle layer including the resin particles is formed on the surface of the intermediate transfer medium by the particle layer forming means (the step of forming the resin particle layer). Numerous cavities are formed between the resin particles in the resin particle layer formed on the surface of the intermediate transfer medium.
Next, ink is jetted by the inkjet recording means from an inkjet recording head onto the resin particle layer formed on the surface of the intermediate transfer medium, with the cavities in the resin particle layer retaining the ink, to record an image (the step of recording). Because the ink is effectively retained in the cavities between the resin particles, drying of the ink is accelerated and problems such as bleeding and stains do not occur even when color images are printed. Moreover, jetted ink droplets do not rebound, whereby problems do not occur at the inkjet recording head. Therefore, various measures for improving image quality become possible.
Then, the resin particle layer retaining the ink is transferred to and fixed on the recording medium by suitable transferring and fixing means to form an image (the step of transferring and fixing). Because the resin particle layer retaining the ink is transferred to the recording medium, an image can be formed on any kind of recording medium without being affected by water absorption and drying properties of the surface of the recording medium. Further, when the resin particles are melted and hardened by fixing to form the resin particle layer, an image made of ink is incorporated into the resin layer, whereby an image having not only excellent resistance to water and light, which are insufficient in images formed solely with dye ink, but excellent ozone resistance as well (these may be generically referred to as xe2x80x9cweather resistancexe2x80x9d in some cases) can be formed.
According to a second aspect of the invention, the invention relates to a method for forming an image comprising at least the steps of: forming a layer including resin particles on a surface of a surface of a recording medium; recording an image by jetting ink from an inkjet recording head onto the resin particle layer so that the ink is retained in cavities of the resin particle layer; and fixing the resin particle layer retaining the ink.
According to the second aspect of the invention, the invention also relates to an apparatus for forming an image comprising at least: means for forming a layer including resin particles on a surface of a recording medium; means for recording the image by jetting ink from an inkjet recording head onto the resin particle layer so that the ink is retained in cavities of the resin particle layer; and means for fixing the resin particle layer retaining the ink.
The effects of the invention are as follows.
First, the resin particle layer including the resin particles is formed on the surface of the recording medium by suitable particle layer forming means (step of forming the resin particle layer). Numerous cavities are formed between the resin particles in the resin particle layer formed on the surface of the recording medium.
Next, ink is jetted by the inkjet recording means from an inkjet recording head onto the resin particle layer formed on the surface of the intermediate transfer medium, with the cavities in the resin particle layer retaining the ink, to record an image (the step of recording). Because the ink is effectively retained in the cavities between the resin particles, drying of the ink is accelerated and problems such as bleeding and stains do not occur even when color images are printed. Moreover, jetted ink droplets do not rebound, whereby problems do not occur at the inkjet recording head. Therefore, various measures for improving image quality become possible. Moreover, because an ink image is formed on the resin particle layer formed on the surface of the recording medium an image can be formed on any kind of recording medium without being affected by water absorption and drying properties of the surface of the recording medium.
Then, the resin particle layer retaining the ink is fixed on the recording medium by suitable fixing means to form an image (the step of fixing). When the resin particles are melted and hardened by fixing to form the resin particle layer, an image made of ink is incorporated into the resin layer, whereby an image having not only excellent resistance to water and light, which are insufficient in images formed solely with dye ink, but excellent ozone resistance as well can be formed.